For conventional RF-ID (Radio Frequency Identification) or NFC (Near Field Communication) antennas, how to deal with adjacent metal objects has been a problem. That is, when these antennas are each accommodated in a communication apparatus, the antenna is placed while being surrounded by a metal part such as a metal case, electromagnetic wave shield, metal plate inside a liquid crystal panel, or a frame for securing strength. Therefore, when an antenna performs communication, an eddy current that weakens the current or magnetic field of the antenna flows through the metal part, thus deteriorating the communication performance of the antennas. The communication performance deteriorates significantly particularly when a metal body is placed in the communication direction of the antenna.
Thus, an antenna apparatus is proposed which will improve the communication characteristics of a loop antenna using a peripheral metal plate (e.g., see PTL 1). That is, a metal plate is provided with a through hole (opening) and a slit, and the through hole and the opening of the loop antenna are arranged to overlap with each other so that the direction of the current flowing through the loop antenna matches the direction of the eddy current flowing through the outer circumference of the metal plate. In other words, the outer circumference of the metal plate is used as an antenna.